Prognostic relevance of serum beta2 microglobulin in patients with follicular lymphoma treated with anthracycline-containing regimens. A GISL study.

Background and Objectives Although serum b2 microglobulin (b2M) is an easy parameter to measure, and overexpressed in a large number of lymphoproliferative diseases, its prognostic value has been largely underestimated. The present study examined the influence of b2M levels on overall survival (OS) of patients with follicular lymphoma (FL). Design and Methods The prognostic role of b2M was evaluated in 236 patients with FL identified from the databases of the Gruppo Italiano per lo Studio dei Linfomi (GISL) and treated with anthracycline-based regimens from 1993 to 2003. Results Elevated serum b2M levels were found in 82 patients (35%). According to multivariate logistic regression analysis, elevated b2M levels were associated with elevated lactate dehydrogenase (LDH) (p=0.021), age (p=0.029), and number of involved nodal areas (p<0.001). The percentage of elevated b2M levels increased progressively with increasing FLIPI scores (17%, 38%, and 63% in the low-, intermediate-, and high-risk groups, respectively). Five-year OS was 61% (95% CI, 47-73%) and 89% (95% CI, 82-93%) for patients with elevated vs normal b2M levels respectively (p<0.001). Cox regression analysis showed that b2M level had an independent and stable prognostic value (HR=3.0; 95%CI, 1.6-5.7). In a multivariate analysis the impact of b2M level on survival was independent of FLIPI score, with a HR of 2.94 (95% CI, 1.54- 5.62). Interpretation and Conclusions Our results demonstrate that in patients treated in the pre-rituximab era, b2M level was an independent prognostic marker in addition to FLIPI score. We thus suggest that b2M be routinely assessed and tested in future prognostic studies of FL patients treated with combination chemotherapy and anti-CD20 agents.